JP6189320B2 - Combination of tire structure and tread pattern for heavy goods transport vehicles - Google Patents

Description

  The present invention relates to a tire for a heavy goods transport vehicle, and more particularly to a tire adapted to be attached to a heavy goods transport vehicle.

  The present invention relates to a tire having a radial carcass reinforcement adapted to be attached to heavy vehicles such as lorries, buses, tractors, trailers, and more particularly to a crown reinforcement of this tire in combination with a tire tread.

  In general, a crown reinforcement comprising a plurality of crown plies rests or is located on the radial outside of the radial carcass reinforcement of the tire in question formed by a non-extensible metal or aromatic polyamide reinforcement element . In a known form, the crown reinforcement includes a triangular structure-forming ply formed by metal elements oriented at an angle in the range of 45 ° to 90 ° with respect to the circumferential direction. The ply itself carries two working plies, which are in parallel with each other in each ply and have a crossing relationship between one ply and the next ply and in the circumferential direction. It is formed by a non-extensible metal reinforcing element that makes an angle ranging from 10 ° to 45 °. These active plies that form the active reinforcement are covered with at least one ply called a protective ply, which is essentially against damage that may be caused by foreign objects entering the groove of the tread. Help protect production ply.

  A metal reinforcement element called “extensible” or an element called “elastic”, that is, a force-elongation curve may be formed of elements that exhibit relatively large elongation under small tensile forces. In this case, the reinforcing elements of the protective ply are generally directed in the same direction and in absolute value at the same angle as the reinforcing elements of the radially outermost active ply and the radially outermost active ply As a whole, the width is narrower in the axial direction. This protective ply may be made of any material and with any structure that serves the purpose of protecting the active reinforcement and is made of a homogeneous material in the form of a circumferentially wound band or ply. Can be considered for use.

  In combination with this internal reinforcement structure, it provides a tread, that is, a tread pattern formed by grooves and slits in a portion of the tire that gradually contacts the road surface when the tire is rolling. This is a known method.

  In this application, a slit is distinguished from a groove, the distinction being that the slit is narrow and generally allows contact between the opposing walls that define the slit during travel, especially during the passage of a footprint, This is not the case with the groove under normal tire usage conditions.

  US 2010/0269967 describes a heavy duty tire having a radial carcass reinforcement with a crown reinforcement centered on the equator plane, the crown reinforcement itself There is a tread on top. The crown reinforcement includes a plurality of active plies carrying a protective ply that is substantially smaller in width than the narrowest active ply. This protective ply is arranged radially in two grooves arranged symmetrically with respect to the equatorial plane. On the outside in the axial direction of these two grooves, the tread is provided with grooves on each side having the same depth as the other two grooves. In order to obtain high performance in terms of durability, this structure has a minimum thickness between the bottom of the groove and the last working ply of the working ply in the region located axially beyond the protective ply. I need that.

  WO 2011/002454 describes a tire made by retreading, which has a carcass with a crown reinforcement on the radial outside and the crown reinforcement itself A tread that has been vulcanized in advance is on the top. The tread has a plurality of grooves opened to the outside and a groove opened on the inner face of the tread. The latter groove is provided to form a new groove after partial wear of the tread. The inner and outer groove sets are arranged radially on the ply set that forms the crown reinforcement. The edge side rib formed in this way is relatively rigid. This is because a pair of crown reinforcement plies are present in the edge ribs.

  Combined with the tread pattern, it allows for a good optimization of rolling resistance, durability and leveling performance when in contact with the road surface, while optimal safety regardless of tire wear There is a need for a tire structure for a heavy-duty vehicle that provides improved performance.

Definition

  The ratio of voids per unit volume of the tread pattern is determined by the volume (or bulk) of voids (particularly formed by grooves and cavities) defined by convex elements (blocks and ribs) and the volume of material and grooves and Equal to the ratio of the total volume including the volume of the cavity. A low ratio of voids per unit volume means that the void volume is small relative to the tread volume.

  The block is a convex element formed on the tread, the convex element being defined by a cavity or groove, the convex element having side walls and a contact face, the contact face being in motion, It comes in contact with the road surface.

  The rib is a convex element formed on the tread, and this convex element is defined by two grooves. The rib has two side walls and a contact face, and the contact face comes into contact with the road surface.

  The term “radial direction” means a direction perpendicular to the axis of rotation of the tire (this direction corresponds to the direction of the thickness of the tread).

  The term “axial direction” means a direction parallel to the rotational axis of the tire.

  The term “circumferential direction” means the direction of the tangent of an arbitrary circle whose center is located on the axis of rotation. This direction is perpendicular to both the axial and radial directions.

  “Notch” generally refers to either a groove or a slit, which corresponds to a space defined by walls of material facing each other and separated from each other by a non-zero distance. ing. It is this distance that distinguishes the slit from the groove, and in the case of a slit, this distance allows at least a portion of the opposing walls defining the slit to contact during the passage of the footprint on the road surface. Is set. In the case of a groove, the walls of the groove do not contact each other under normal driving conditions.

  In particular, the tire use conditions defined by the ETRTO standard specify the nominal inflation pressure corresponding to the load capacity of the tire indicated by its load index (load capacity index) and its speed code.

  The footprint on the road surface is determined in a state where the tire is in a static condition, and the average footprint length is calculated based on the static condition.

  The equator plane is perpendicular to the tire's axis of rotation and coincides with a plane that passes through the radially outermost point when the tire is attached to its mounting rim and inflated to its nominal inflation pressure.

US Patent Application Publication No. 2010/0269967 International Publication No. 2011/002454 Pamphlet

  While the present invention provides a good optimization of the performance of heavy duty vehicle tires in terms of rolling resistance and durability, regardless of whether the tire is new or partially worn, It aims to provide optimal user safety.

  Thus, the heavy-duty vehicle tire of the present invention has a carcass reinforcing material on which a crown reinforcing material is mounted, and the crown reinforcing material divides the tire into two equal or substantially equal parts. The tire has a tread with a width W and a total thickness E located radially outward of the crown reinforcement, the tread has a rolling surface, and the total thickness E is the rolling surface Consistent with the total thickness of the material measured on the equatorial plane XX 'between the radially outermost portion of the crown reinforcement and this tread has a maximum thickness PMU of material that becomes worn during travel. The maximum thickness PMU is equal to or less than the total thickness E.

  The crown reinforcement is formed by at least two active plies and a protective ply located radially outward of the active ply and radially inward of the tread, with the narrowest active ply from 70% of the width W of the tread. Having a width in the range of up to 90%.

  The working ply is a rain forcer or reinforcement oriented at an angle in the range of 15 ° to 25 ° with respect to the circumferential direction of the tire, in particular to contribute to the balancing of forces associated with tire pressure. Consists of elements. The protective ply serves to protect the production ply, and this protective ply is generally reinforced by a rain forcer that exhibits a force-elongation curve with two different slopes that are subjected to a small force. (This is different from the actual ply reinforcer).

  The tread of the present invention is provided with grooves only at portions located radially outside the protective ply and between the axial ends of the ply, and each groove directed in the circumferential direction has a maximum wear thickness PMU. Having a depth equal to at least 75%.

This tire is characterized by the following contents.
The protective ply has a width equal to at most 70% of the width of the smallest working ply in the axial direction;
-The tread is axially, generally circumferential, between the axial end of the narrowest working ply and the axial end of the protective ply (the two ends are located on the same side of the equatorial plane) Having a channel directed to (i.e., extending around the entire tire), the channel being at least one new after partial wear equal to at least 50% of the maximum thickness PMU of the material to be worn. The channel is formed such that the minimum distance between the channel and the working ply and the minimum distance between the channel and the protective ply are different from zero.

  In a modification of the present invention, the tread has a plurality of ribs including two shoulder side ribs, and each shoulder side rib having a width M is viewed in the axial direction from the groove opened on the outside of the tread and the equator plane. The width M of each shoulder rib is equal to at least 1.5 times the width of the other ribs.

  In another variation, the tread of the present invention is provided with a slit as an extension of each channel toward the rolling surface in the thickness of the tread in the new condition, the slit being at least partially during the passage of the footprint. Such that it has a suitable geometric shape that can be closed. This configuration is particularly advantageous when the width of the shoulder rib is given, because this configuration allows bending and thus regaining flexibility during leveling during the passage of the footprint.

  In a variation of the invention, the tread is in a new condition and the volume of the voids in each channel is the whole of the voids formed by the set of channels, grooves and slits, regardless of the orientation of the channels, grooves or slits. It is such that it is 2% or more and 15% or less of the volume.

  In a variation, the tread of the present invention is such that the total volume of the voids in the tread in the new state is 18% or less of the total volume of material that becomes worn during travel, ie, the volume corresponding to the thickness PMU. It is a thing.

  In another variation, the tread of the present invention is such that each slit is defined by faces facing each other, the faces having means to mechanically restrain the relative movement of the faces relative to each other.

  In another variant, the tread of the present invention is such that each channel extends to a depth greater than the maximum thickness PMU of the material that becomes worn in the thickness of the tread and at most over the entire thickness E. .

  In another variation, the tread of the present invention has a geometrical shape in which at least one circumferential channel is “undulated” at least in the direction of the thickness of the tread, so that after the channel is properly worn, It is like that there is no continuous opening on the rolling surface.

  In another variant, the tread of the present invention is such that at least one circumferential channel having a wavyly contoured geometry is formed under the rolling surface of the new tread. .

  In another variation, the tread of the present invention has a geometric shape in which at least one circumferential channel is “undulated” in at least a direction parallel to the tire's axis of rotation, and therefore this channel is the axis of rotation. It seems like it is still located at the same distance. This variant is particularly useful because the position of the side channel is variable with respect to the end of the protective ply, thus reducing the stress.

  In another advantageous variant, at least one additional channel is provided connected to a circumferential channel formed between the end of the protective ply and the end of the axially narrowest working ply. This additional channel also opens into the groove or towards the outside of the tread. This configuration results in a kind of network that allows the air to circulate from the inside to the outside and vice versa, i.e. from the outside to the inside, and thus a good temperature at the edge of the tread. Adjustment is promoted.

  Advantageously, the above-described tread of the present invention is provided for attachment to a tire whose recommended use is to be attached to a drive axle of a heavy-duty transport vehicle. Advantageously, the tire has means to direct this preferred use.

  Other features and other advantages of the present invention will become apparent from the following description, provided with reference to the accompanying drawings, which illustrate, by way of non-limiting examples, the various proposed by the present invention. An embodiment is shown.

It is sectional drawing of the tire as a 1st form of this invention. It is sectional drawing of the tire as another form of this invention. It is a top view of the tread of the tire of FIG. It is a figure which shows another form of the tire of this invention with which the channel undulates in the depth of the tread. FIG. 5 is a side view of a part of the tread of FIG. 4. It is a figure which shows the modification of this invention in which the slit which has a wavy undulation part in the thickness of a tread is provided as an extension part of the channel which goes to a rolling surface.

  In the drawings attached to this specification, the same reference numerals can be used to describe the embodiments of the present invention, and these reference numerals indicate elements of the same kind in terms of structure or function. ing.

FIG. 1 is a partial view of a half of a 315 / 70R22.5 size tire, which has two beads, with an extension of the two beads as a sidewall joined at the crown. The tire is reinforced by a radial carcass reinforcement composed of a single ply 1 of metal cord. The crown of the tire has a crown reinforcing material on which the tread 2 is placed at a radially outer position, and the tread 2 has a rolling surface 20. The carcass reinforcing material is fixed to the bead core in each bead so as to form a folded portion. On this carcass reinforcing material, a crown reinforcing material 3 is placed at a radially outer position, and the crown reinforcing material 3 is radially directed from the inside to the outside.
-Having a first crown ply 30 called "triangular forming ply" composed of metal cords, these cords being oriented at an angle equal to or close to 65 ° with respect to the circumferential direction; (The circumferential direction is perpendicular to the plane of FIG. 1),
-Having a first working ply 31 composed of a metal cord positioned or resting on this crown ply 30 and forming an angle of 18 [deg.] With the circumferential direction, the triangular structure forming ply 30 and the first working ply 30 The cord of the ply 31 has the same direction with respect to the circumferential direction, in which case half of the total axial width L1 of this working ply is equal to 252 mm (this half width is equal to the equator plane XX ′). Measured between the end 310 of the working ply 31),
-Next, it is the same as the metal cord of the first working ply 31 and is made of a metal cord, and the circumferential direction and the angle of the first working ply 31 are opposite in sign. A second working ply 32 composed of a metal cord having an angle expressed in absolute value equal to 18 °, the total axial width rib 2 of the second working ply being equal to 232 mm,
-Finally, located on this second working ply 32 on both sides of the equator plane, expressed in the same direction and in absolute value with respect to the circumferential direction as the angle of the metal cord of the second working ply It has a protective ply 33 made of a metal cord directed at an angle equal to the lever angle, and this protective ply serves to protect the working ply from external damage during travel. The protective ply cord has a relative elongation of 0.2% or less when subjected to a tensile load equal to 10% of the breaking load.

  The width Lp of the protective ply is equal to 124 mm.

  The total width W of the tread, which corresponds to the width of the footprint in use conditions, is equal to 280 mm. The plies forming the set of crown reinforcements 3 are positioned so as to be equally distributed on both sides of the equatorial plane XX ′.

  A groove 4 is provided on each side of the equatorial plane XX ′ in the portion C of the tread located radially outside the protective ply 33 and having the same width as the protective ply 33. It has a depth of 20 mm. The width of the groove 4 varies with the depth, and this width is equal to 10.5 mm on the rolling surface 20 in the new state, and this width is 4 mm at 1.6 mm from the bottom 40 of the groove. be equivalent to. This tread 2 is also designed to allow "regrooving", i.e., before reaching the wear limit level, each groove 4 is treated by a mechanical cutting operation, thereby increasing the average depth. Can regenerate 3 mm grooves. In this case, the maximum height of the material in the wear state corresponding to the thickness PMU is 23 mm in the new state (3 mm provided for groove regeneration is added to the depth of 20 mm of the groove 4). equal. In addition, the protective ply 33 is located at a distance D of 5 mm from the bottom of the groove 40, so that after regenerating the thickness of the material of 2 mm between the protective ply 33 and the groove bottom 40. Can be held in. The total thickness E of the tread is measured between the rolling surface and the outside of the protective ply 33 on the equator plane in the new state, in which case the total thickness T of the tread is equal to 25 mm.

  A circular cross-sectional channel 5 having a diameter of 6 mm is formed between the end 330 of the protective ply 33 and the end 320 of the outermost working ply 32 in the axial direction. The channel 5 directed in the circumferential direction is positioned so as to be entirely present in the tread in a new state, and more precisely, is positioned at a distance of 14 mm from the rolling surface 20. In this case, the bottom 51 of this channel 5 (corresponding to the channel located closest to the inside of the tread) is located at the same distance from the rolling surface 20 as the bottom 40 of the groove in the new state. To do.

  The minimum distance F between the point defining this channel 5 and the end 330 of the protective ply 33 located on the same side of the equatorial plane XX ′ is equal to 20 mm, while this from the radially outermost working ply 32 The minimum distance K where the channel 5 is defined is equal to 7 mm.

  The circumferentially directed channel 5 extends around the entire tire, and is provided with a slit 6 as an extension of the channel radially outward, and is open on the rolling surface 20 in a new state. The width of this slit is equal to 3.5 mm. The slit 6 opens into the channel 5 having a width of 2 mm. The dimension of the slit 6 is such that this slit is at least partly closed during its passage of the footprint on the road surface and can therefore close the channel 5 so that the tire is running. The entry of foreign objects that may be present on the road surface is prevented.

  A running test was carried out. In this running test, the tire of the present invention has the same size tire in which additional grooves are formed in place of the channels while the protective ply extends axially beyond these grooves. Compared with. The other reinforcements in both the carcass and crown were the same as the tire reinforcement of the present invention. According to these test results, the tire of the present invention has an advantage in terms of rolling resistance (that is, energy consumption is reduced during running) and braking performance when the tire is partially worn. A significant improvement was obtained. Furthermore, the tires of the present invention showed a marked improvement in performance in terms of the entry of objects into the tread, and as a result, the durability of the crown reinforcement was increased.

  The variant shown in FIG. 2 has some of the same characteristics as the tire shown in FIG. However, the channel is formed to follow a wavyly undulating path on the substantially cylindrical surface S whose axis coincides with the tire's axis of rotation. Thus, the channel 5 is located at a constant or practically constant distance from the rolling surface of the tire in the new state. The point located furthest inward in the radial direction from this channel is located at a depth close to or possibly equal to the total thickness E of the tread. This configuration does not have a slit as an extension of the channel going outward, i.e. towards the rolling surface in the new state. This channel is formed by molding on the radially inward side of the tread, if necessary, with a slit open to this radially inner surface of the tread, if necessary, before the tread is applied to the tire blank. It is good. The advantage of providing this configuration is that the susceptibility of the ends 330 of the protective ply 33 to damage is further reduced by moving the channel at least partially away from these ends.

  FIG. 3 partially shows a plan view of the form shown in the cross-section of FIG. 2, in which the wavy geometric shape followed by the channel 5 in the lateral part B of the tread is visible. .

  The last-mentioned configuration can be modified so that the channel at least partially overlaps the end of the narrowest working ply.

  In the form shown in FIG. 4, each channel 5 may be undulated so as to alternately approach or move away from the rolling surface 20 in a new state. In this configuration, the channel 5 is extended to the rolling surface 20 by the slit 6. Obviously, this configuration can be combined with the configuration shown in FIGS. 2 and 3, resulting in channel undulations in both tread thickness and width. FIG. 5 is a cross-sectional view taken along the plane indicated by the letters VV in FIG. In this cross-sectional view, it can be seen that the channel 5 is wavy to approach the rolling surface 20 and then away from it. In this configuration, it is desirable to provide an additional channel, each end connected to the portion of the corrugated channel 5 located farthest from the rolling surface 20 and at the other end of the groove 4.

  In another form shown in FIG. 6, a slit 6 having a substantially constant width is provided as a radial extension of each circumferential channel 5 towards the rolling surface 20 of the tread in the new state, On the walls defining it, there are means for mechanically restraining the relative movement of these walls. In this form, the slit 6 takes a zigzag geometric shape in the thickness of the tread. This configuration can not only limit the reduction in stiffness caused by the presence of the slit, but also limit the risk of foreign material entering the underlying channel.

  Regarding all of the above-mentioned forms, it can be said that it is also desirable to appropriately change the properties and characteristics of the constituent material of the tread in the region indicated by the letters B and C in FIGS.

  This configuration also shows a plurality of lateral grooves 8 that originate in the circumferential channel 5 and open at the other end into the circumferential groove. This advantageous configuration allows a single ventilation or circulation by circulation from the groove to the channel through the transverse channel connecting the groove to the circumferential channel, in the tread and as close as possible to the region near the edge of the crown reinforcement. The advantage of providing a ventilation format is provided. In view of this combination of grooves and circumferential and transverse channels, a kind of network is formed on the surface and below the new rolling surface.

  In another form not shown, each channel directed in the circumferential direction as a whole is combined with a plurality of laterally directed channels, the latter of these laterally directed channels in particular in the rain When running on the tread, an opening is made on the outer sidewall of the tread to facilitate lateral drainage of the fluid and further promote good ventilation or ventilation of the portion of the tread located near the axial end of the crown reinforcement.

  While the invention has been generally described and supported by many forms, it should be understood that the invention is not limited to only these forms. Obviously, various modifications may be made to such configurations without departing from the general scope of the invention. In particular, the number of channels may be two or more on each side of the equatorial plane depending on the size and / or use of the tire. Similarly, these circumferentially directed channels may also be provided below the rolling surface in the new state and connected to other channels that open laterally on the tread side, for example.

  All of the forms described can advantageously be combined with one another according to the aim of the person skilled in the art using the present invention.

Claims (10)

A tire for a heavy-duty transport vehicle, wherein the tire has a carcass reinforcement (1) on which a crown reinforcement (3) is mounted, the crown reinforcement comprising two equal or substantially different tires Extending on each side of the equatorial plane XX ′ divided into equal parts, the tire has a tread (2) with a width W and a total thickness E located radially outward of the crown reinforcement (3), The tread has a rolling surface (20), and the total thickness E is equal to the equatorial plane XX 'between the rolling surface (20) and the radially outermost portion of the crown reinforcement (3). Consistent with the total thickness of the material measured above, the tread (2) has a maximum thickness PMU of the material that becomes worn during travel, the maximum thickness PMU being at most the total thickness E. Equally, the crown reinforcement (3) has at least two working plies ( 1, 32) and a protective ply (33) positioned radially outward of the working ply and radially inward of the tread, the narrowest active ply (32) of the width W of the tread Each tread having a width in the range of 70% to 90%, the tread having grooves provided only in a radially outer portion of the protective ply (33), and being directed in the circumferential direction Has a depth of at least 75% of the maximum thickness PMU to be worn, and the tread extends around the entire tire and is at least 50 of the maximum thickness PMU of the material to be worn. % Of the channel (5) oriented circumferentially as a whole so as to form at least one new groove after partial wear equal to%, said channel (5) In the heavy-duty vehicle tire, the minimum distance between the working ply (31, 32) and the minimum distance between the channel and the protective ply (33) is not zero. The protective ply (33) has a width equal to at least 70% of the width of the narrowest active ply (32), and the channel (5) is the narrowest in the axial direction. A heavy goods carrying vehicle tire formed between an axial end of an actual ply and an axial end (330) of the protective ply (33) located on the same side of the equatorial plane.   The tread has a plurality of ribs including two shoulder-side ribs, and each shoulder-side rib having a width M is furthest from the groove opened on the outside of the tread and the equatorial plane when viewed in the axial direction. 2. The heavy-duty vehicle tire according to claim 1, wherein the tire is defined by a position of the tread, and the width M of each shoulder-side rib is equal to at least 1.5 times the width of the other rib.   A slit (6) is provided as an extension of each channel (5) toward the rolling surface (20) in the thickness of the tread in a new state, and the slit (6) is a foot of the slit (6). 3. Heavy duty vehicle tire according to claim 1 or 2, having a geometric shape suitable for being at least partially closed during the passage of the print.   In the new state, the volume of the void in each channel (5) is the total volume of the void formed by the set of the channel, the groove and the slit, regardless of the orientation of the channel, the groove or the slit. The heavy-duty vehicle tire according to any one of claims 1 to 3, wherein the tire is 2% or more and 15% or less of the volume.   Each channel (5) extends to a depth greater than the maximum thickness PMU of the material to be worn in the thickness of the tread and at most over the entire thickness E. The heavy-duty vehicle tire described in 1.   At least one circumferential channel (5) has a wavy geometric shape at least in the direction of the thickness of the tread, so that the channel is suitable for the rolling surface (20) after suitable wear. The heavy-duty vehicle tire according to any one of claims 1 to 5, wherein the tire does not continuously open upward.   7. Heavy goods transport according to claim 6, wherein the at least one circumferential channel (5) having a wavy geometric shape is formed entirely under the rolling surface of the new tread. Tires for vehicles.   The at least one circumferential channel (5) has a wavy geometric shape at least in a direction parallel to the axis of rotation of the tire, so that the channel is located at the same distance from the axis of rotation. The tire for heavy goods transport vehicles as described in any one of Claims 1-5 which is made to remain.   At least one additional channel (8) connected to a circumferential channel (5) formed between the end of the protective ply (33) and the end of the axially narrowest active ply (32) 9. Heavy goods transport vehicle according to any one of the preceding claims, wherein the additional channel (8) is also open in the groove or towards the outside of the tread. Tires.   The said tire has a means to instruct | indicate that the said tire is suitable for being attached to the drive axle of a heavy-duty conveyance vehicle, The tire for heavy-duty conveyance vehicles as described in any one of Claims 1-9.

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